Prophylactic mastectomy may not boost survival

Despite the lack of evidence suggesting that contralateral prophylactic mastectomy improves overall survival among women with breast cancer, recent years have seen an alarming increase in the number of women choosing to undergo the procedure.

Heightened public awareness of hereditary breast cancer and genetic testing improvements in both mastectomy approaches and breast reconstruction techniques, and increased use of breast MRI, which is more sensitive to the identification of “suspicion spots”, may be driving the increase in contralateral prophylactic mastectomies (CPMs) said at a breast cancer meeting sponsored by Harvard Medical School, Boston.

It was noted however, that the existing data on disease recurrence and survival suggest the radical, irreversible procedure maybe unnecessary for most patients. “Although (CPM) reduces the risk of contralateral breast cancer by more than 90 percent, the annual risk of contralateral breast cancer is extremely low, about 0.7 percent, and there are few data indicating that the procedure improves overall survival.

Many women who chose CPM do so at an especially vulnerable time and without sufficient thought or counseling about their risk-reduction options, said at the University of Minnesota, Minneapolis. Removing the second breast seems like a surefire way to avoid recurrence, although the reality is that, in advanced breast cancer, the risk of systemic metastases exceeds the risk of contralateral breast cancer.

In an investigation last year, a national database was used to review the treatment of patients with unilateral breast cancer who were diagnosed between 1998 and 2003. The investigators determined that of the approximately 153,000 women diagnosed with stage I, II, or III cancer, nearly 60,000 women underwent a single mastectomy and nearly 5,000 women who were candidates for the single procedure opted for a double mastectomy. The rate of the CPM procedure rose from 4 percent in 1998 to 11 percent in 2003.

Because patient-physician interaction plays an important role in the breast cancer treatment decision process, it is critical that physicians provide clear accurate information so patients can understand their option. Among the alternatives to CPM that should be discussed are surveillance with clinical breast examination, mammography and breast MRI, tamoxifen, and aromatase inhibitors.

With respect to the surveillance option, “studies have shown that patients with unilateral breast cancer who are closely monitored develop significantly smaller tumors in the contralateral breast and have lower rates of axillary lymph node metastases relative to unscreened patients’. Because the annual risk of contralateral breast cancer is constant, such surveillance should continue indefinitely, it was noted.

Regarding hormonal prophylaxis, data from the National Surgical Adjuvant Breast and Bowel project protocol B-14 showed a significant reduction in contralateral breast tumor in women with node-negative, estrogen receptor-positive breast tumors who were treated with tamoxifen for at least five years, compared with placebo-treated women. In addition, several international trials have shown that aromatase inhibitors reduce the risk of contralateral breast cancer as much as or more than tamoxifen in postmenopausal women with early-stage breast cancer that is hormonic receptor-positive/estrogen receptor-positive, progesterone receptor-positive or both.

These alternatives are particularly reasonable for patients who are at average risk of contralateral breast cancer who are good candidates for breast-conserving treatment. In some patients with early breast cancer, however, the discussion regarding (CPM) should be initiated. These include patients with known BRCA mutations or those who have previously undergone chest radiation therapy, because of the associated increased risk of contralateral breast cancer; patients with dense breast tissue on mammography, a strong family history of breast cancer absent a genetic mutation, or lobular carcinoma in situ; and patients who are not good candidates for breast-conserving surgery because of tumor size, multiple tumors, or contraindications for breast radiotherapy.

For patients with advance-stage cancer in whom the risk of systemic metastases is greater than the risk of contralateral breast cancer, there are no clear benefits to CPM, noting that complications from the procedure could potentially delay necessary chemotherapy or radiation treatment.

It is the role of the physician to enable women with breast cancer to make informed treatment decision. For example, if a patient decides to undergo (CPM) because she thinks it will allow her to live longer, her physicians has to explain that the procedure will not necessarily improve her chances of long term survival. –Charles C. Chante, MD (The Philippine Star)